Structural and mechanical properties of polypropylene nanofibres fabricated by meltblowing

In this paper, a novel technique for the fabrication of nanofibres of polypropylene by meltblowing process with the injection of different fluids (such as nitrogen and water) has been explained. Low molecular weight polypropylene polymers were used in this study. The surface morphology of nanofibres was analysed by scanning electron microscopy. It was observed that the use of water gave better results compared to nitrogen for the fabrication of nanofibres. Nuclear magnetic resonance studies revealed similar chemical shifts for polymers and nanofibres, which indicated no change to the chemical functionality of the nanofibres by the application of fluids and high temperature during meltblowing. The mechanical properties of the nanofibres were investigated by using dumb-bell-shaped specimens in a universal tensile tester. The fibres fabricated with nitrogen were weaker and lower in tensile modulus compared to the fibres fabricated with water. The use of a rotating collector increased the tensile strength compared to a stationary collector due to higher degree of fibre alignment in the rotating drum. The tensile strength and modulus values were increased after annealing due to the increase in the crystallinity. The meltblown nanofibres showed hydrophobic nature as indicated by the high values of water contact angle. The hydrophobicity of the nanofibres fabricated with the injection of fluids did not change noticeably from the as-spun fibres fabricated without the fluids.